Temperature patterns and mechanisms influencing coral bleaching during the 2016 El Niño

Tim R. McClanahan*, Emily S. Darling, Joseph M. Maina, Nyawira A. Muthiga, Stéphanie D'agata, Stacy D. Jupiter, Rohan Arthur, Shaun K. Wilson, Sangeeta Mangubhai, Yashika Nand, Ali M. Ussi, Austin T. Humphries, Vardhan J. Patankar, Mireille M. M. Guillaume, Sally A. Keith, George Shedrawi, Pagu Julius, Gabriel Grimsditch, January Ndagala, Julien Leblond

*Corresponding author for this work

    Research output: Contribution to journalLetterpeer-review

    35 Citations (Scopus)


    Under extreme heat stress, corals expel their symbiotic algae and colour (that is, ‘bleaching’), which often leads to widespread mortality. Predicting the large-scale environmental conditions that reinforce or mitigate coral bleaching remains unresolved and limits strategic conservation actions1,2. Here we assessed coral bleaching at 226 sites and 26 environmental variables that represent different mechanisms of stress responses from East Africa to Fiji through a coordinated effort to evaluate the coral response to the 2014–2016 El Niño/Southern Oscillation thermal anomaly. We applied common time-series methods to study the temporal patterning of acute thermal stress and evaluated the effectiveness of conventional and new sea surface temperature metrics and mechanisms in predicting bleaching severity. The best models indicated the importance of peak hot temperatures, the duration of cool temperatures and temperature bimodality, which explained ~50% of the variance, compared to the common degree-heating week temperature index that explained only 9%. Our findings suggest that the threshold concept as a mechanism to explain bleaching alone was not as powerful as the multidimensional interactions of stresses, which include the duration and temporal patterning of hot and cold temperature extremes relative to average local conditions.

    Original languageEnglish
    Pages (from-to)845-851
    Number of pages12
    JournalNature Climate Change
    Publication statusPublished - Nov 2019


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